Method of preparing tertiary phosphine oxides using elemental phosphorus



3,099,684 METHOD OF PREPARING TERTIARY PHOSPHINE OXIDES USING ELEMENTAL PHOSPHORU Michael M. Rauhut, Norwalk, and Andrew M. Semsel, Stamford, Conn, assignors to American Cyanamid Company, New York, N.Y., a corporation of Maine No Drawing. Filed Apr. '7, 1961, Ser. No. 101,329 Claims. (Cl. 2619-485) The present invention relates to novel organo-phosphorus compounds and to the preparation of same. More particularly, the instant discovery concerns new and useful tertiary phosphine oxides prepared by a novel and straightforward method.

According to the present invention an alkyl acrylate of the formula i C H wherein R may be alkyl, branched or straight chain, having from 1 to 12 carbon atoms, Y may be H, lower alkyl, phenyl, or the like, and Z may be H, lower alkyl, and -CH CH COOR, wherein R is alkyl (C -C is reacted with elemental phosphorus and a strong base in the presence of water, as will be shown, to produce the corresponding tertiary phosphine oxide having the formula wherein R, R, Z and Y have the meaning given above.

Pursuant to a typical embodiment of the present invention the following reaction is made to take place and super-atmospheric pressures. At high temperatures,

say, from 0-175 C., super-atmospheric pressures are generally employed, as is evident to the person skilled in the art. Batch, continuous or semi-continuous processes may be employed.

According to a preferred embodiment, an aqueous strong base is employed. Typical strong bases Within the purview of the instant discovery are the alkali metal hydroxides, the alkaline earth metal hydroxides, and the like, such as Na, Li, K hydroxide, Ca, Ba hydroxide, etc. If desired, reaction is made to take place in the presence of a solvent. Typical solvents are acetonitrile, alkanols, such as methanol, ethanol, propanol, butanol, t-butyl alcohol, ethers, such as dioxane, diethoxyethane, diethylether of diethylene glycol, tetrahydrofuran, and the like, dimethylformamide, dirnethylsulfoxide, pyridine, and numerous other like solvents which under the conditions of the reaction do not interfere with the production of the desired products.

Typical acrylate reactants of the formula i O H above, are methyl acrylate, ethyl acrylate, t-butyl acrylate, t-butyl methacrylate, Z-ethylhexylacrylate 2-ethylhexylcrotonate, Z-ethylhexylcinnamate, diethyl-Z-methyleneglutarate, and the like.

Generally, the reactants contemplated herein are brought together in stoichiometric amounts, ,as demonstrated by the illustrative specific embodiment above. However, an excess of any of these reactants with respect to the other reactant may be employed and the amount of excess is governed by practicality.

The products of the present invention are useful as fire retardants for cotton cloth. For example, cotton cloth dipped, according to well-known procedures, in a suitable solution of any one of these tertiary phosphine oxides manifests desirable fire retardance.

The present invention will best be understood by virtue of the following examples which are merely illustrative and not intended to limit the scope of the invention, except insofar as the invention is described in the claims.

EXAMPLE I Tris (Z-carbethoxyethyl)phosphine oxide carefully siphoned from the mixture of aqueous phase 3 4 and unreacted phosphorus. The organic phase is neumethyl sulfione, and the like, to produce the correspondtralized with two drops of concentrated hydrochloric acid, 111g tertiary P P OXldesdried over anhydrous sodium sulfate, and distilled under EXAMPLES IX X1 I reduced pressure to obtain 12.7 grams of tris(2-carb The following table in which the process essentially Xyel1hy1)PhOSPhII1e OXide, bolllllg P 5 according to Example I, above, is repeated illustrates (0.3 millimeter mercury). Upon redistillation an analytithese embodiments.

TABLE II Ex. Reactant Solvent Base 'Ileigp. Product IX Vinyl methyl ketone GH3CN KOH... 30-35 (CHa CHzCHQa X Tetrafluoroethyle'ne Dimethylformamide. NaOH 0-40 (F2CHCF2)sPO l XL--. Vinyl methylsulfone t-Butanol NaOH 50-75 (CHsSI:CHzCHz)a 0 XII--. Chlorotrifluoroethylene Pyridine NaOH 0-40 (ClFI-ICCFr)aP=0 1 Run in closed system (autoclave) at 50-200 pounds per square inch gauge.

cal sample is obtained, boiling point 199' C.'3 C. Clearly, the instant discovery encompasses numerous (0.2 millimeter mercury), N 1.4682. modifications within the skill of the art. Consequently, Analysis calculated for C H O P: C, 51.42; H, 7.77; while the present invention 'has been described in detail P, 8.84. Found: C, 51.85; H, 7.58; P, 8.84. with respect tohspecgiiaegitgdigfigiug rggfiigags; EXAMPLE ILVH'I h g fifie 353 gi the i nvention, except insofar as they Example I, above, is repeated in every essential respect appear in the appended claims. except as indicated in the following table: While Examples IX through XII define further reactants TABLE I Ex. Reactant Solvent Base T erip. Product II Methyl acrylate CHaCN KOH. 75-100 (HaCOOCCHzCHghPO CH3 III t-Butylmethacrylate CZHEOH Ba(0H)1 75- 80 [(CHmCOOOCHZhPO H IV Diethyl-2-methylene-glutarate... (CHahCOH NaOH..-. 25-50 H C OOCCH CH JOH P'O 0000213 3 V t-Butylacrylate (CHSMOOH KOH----. 35- 40 [(CH )3COOCCH CH P0 VI zethylhexylaerylate CHaCN KOH.. 35- 40 (H9C4CHCH 0OOOH CHmP0 zHg VII Zethylhexylcrotonate Dimethy1-f0rmamide.- Oa(0H)1. 80-100 (H9C4CHCH2OOCCH2CHGH3)3PO l-2H5 VIII.-. Zcthylhexyleinnamate 2-ethy1hexan0l Ca(OH) 80-100 (H 0 CHOHQOOOCH CHC HmPO According to still further embodiments of the present which, like the alkyl acrylates described hereinabove, have invention the acrylate reactants of the formula electronegative substituents, the present invention is not 0 Z Y restricted to alkyl acryl ates and said additional reactants g I (IXXII). By electronegative substituent is meant a substituent having a sigma (par-a) constant greater than about given lh'ereinabove may be replaced by vinyl methyl ke- +0.3, where the sigma constant is defined in A Rewaluatone, tetrafluoroethylene, chlorot'rifluoroethylene, vinyl tion of the Hammett Equation, .by H. H. JalT, Chem.

3 Reyes, 53, 191 (1957). Typical examples of these substituents follow;

Substituent a,

-C Ha 0. 516

N (CH1): 0. 859

S C H3 0. 728

We claim: 1. A method of preparing a tertiary phosphine oxide of the formula 0 z Y (Masada it t which comprises reacting an alkyl acryl'ate of the formula z Y ROG-( 3 63 wherein R, Z and Y have the meanings given above, with elemental phosphorus, a base, and water, in the presence of an inert solvent, and recovering the corresponding tertiary phosphine oxide.

2. The method of claim 1 wherein the alkyl acryl-ate is ethyl aerylate.

3. The method of claim 1 wherein the alkyl acrylate is methyl acrylate.

4. The method of claim 1 wherein the alkyl acrylate is t-butyl methacrylate.

5. The method of claim 1 wherein the alkyl acrylate is t-buty1 Iacrylate.

6. A method of preparing a tertiary phosphine oxide which comprises reacting, in the presence of an inert solvent, elemental phosphorus, a base and water with a member selected from the group consisting of tetrafluoroethylene, chlorotrifiuoroethylene, and a vinyl reactant in which the vinyl moiety is substituted with an electronegative substituent having a sigma (para) constant greater than about +0.3, and recovering the corresponding tertiary phosphine oxide.

7. The method of claim 6 wherein the reactant is vinyl methyl ketone.

8. The method of claim 6 wherein the reactant is tetrafluoroethylene.

9. The method of claim '6 wherein the reactant is vinyl methyl sulfone.

10. The method of claim 6 wherein the reactant is chlonotrifluoroethylene.

References Cited in the file of this patent Kosolapoff: Organo-Phosphonous Compounds, John Wiley and Sons, Inc, 1950, pages 108-109.

Rauhut et al.: Journal of the American Chemical Society, vol. 8 1, No. 5, Mar. 5, 1959, pages 1103-1107. 

1. A METHOD OF PREPARING A TERTIARY PHOSPHINE OXIDE OF THE FORMULA
 6. A METHOD OF PREPARING A TETIARY PHOSPHINE OXIDE WHICH COMPRISES REACTING, IN THE PRESENCE OF AN INERT SOLVENT, ELEMENTAL PHOSPHORUS A BASE AND WATER WITH A MEMBER SELECTED FROM THE GROUP CONSISTING OF TETRAFLUOROETHYLENE, CHLOROTRIFLUOROETHYLENE, AND A VINYL REACTANT IN WHICH THE VINYL MOIETY IS SUBSTITUTED WITH AN ELECTRONEGATIVE SUBSTITUENT HAVING A SIGMA (PARA) CONSTANT GREATER THAN ABOUT +0.3, AND RECOVERING THE CORRESPONDING TERTIARY PHOSPHINE OXIDE. 